Self cleaning, steam cooled, gas sample probe

A gas sampling probe adapted for installation in an industrial furnace for removing sample portions of the gaseous atmosphere within such furnace, comprising a shield tube having an open end for placement within the furnace;

• a sample tube concentrically disposed within the shield tube and spaced therefrom to provide an annular passage for a coolant fluid, said sample tube terminating within the shield tube in an open end that is protectively surrounded by said shield tube;
• a partition plate extending across said annular passage between the shield tube and the sample tube adjacent to the open end of the latter, said partition plate being secured to the shield tube but terminating short of the sample tube, so as to permit free expansion and contraction of such sample tube and provide restricted passage for coolant fluid toward and past the open end of the sample tube to keep it clean;
• means for introducing a coolant fluid into said annular passge at or near the other end of the shield tube;
• port means at one side of the shield tube and at the side of the partition plate that is away from the open ends of the tubes, so as to discharge a major amount of the coolant fluid from the annular passage into a stream of furnace gas flowing past the probe;
• and means discharging sample gas from the sample tube at or near the other end thereof, so that the flow of that portion of the coolant fluid that passes by the partition plate in said annular passage is in substantially the opposite direction to the flow of said sample gas.